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The CIELO collaboration has studied neutron cross sections on nuclides that significantly impact criticality in nuclear technologies – 16O, 56Fe, 235,8U and 239Pu – with the aim of improving the accuracy of the data and resolving previous discrepancies in our understanding. This multi-laboratory pilot project, coordinated via the OECD/NEA Working Party on Evaluation Cooperation (WPEC) Subgroup 40 with support also from the IAEA, has motivated experimental and theoretical work and led to suites of new evaluated libraries that accurately reflect measured data and also perform well in integral simulations of criticality.

Numerous domains, in fundamental research as well as in applications, require the study of reactions induced by neutrons with energies from few MeV up to few tens of MeV. Reliable measurements also are necessary to improve the evaluated databases used by nuclear transport codes. This energy range covers a large number of topics like transmutation of nuclear waste, design of future fission and fusion reactors, nuclear medicine or test and development of new detectors. A new facility called Neutrons For Science (NFS) is being built for this purpose on the GANIL site at Caen (France). NFS is composed of a pulsed neutron beam for time-of-flight facility as well as irradiation stations for cross-section measurements. Neutrons will be produced by the interaction of deuteron and proton beams, delivered by the SPIRAL-2 linear accelerator, with thick or thin converters made of beryllium or lithium. Continuous and quasi-mono-energetic spectra will be available at NFS up to 40 MeV. In this fast energy region, the neutron flux is expected to be up to 2 orders of magnitude higher than at other existing time-of-flight facilities. In addition, irradiation stations for neutron-, proton- and deuteron-induced reactions will allow performing cross-section measurements by the activation technique. After a description of the facility and its characteristics, the experiments to be performed in the short and medium term will be presented.

The TALYS Evaluated Nuclear Data Library (TENDL) has now 8 releases since 2008. Considerable experience has been acquired for the production of such general-purpose nuclear data library based on the feedback from users, evaluators and processing experts. The backbone of this achievement is simple and robust: completeness, quality and reproducibility. If TENDL is extensively used in many fields of applications, it is necessary to understand its strong points and remaining weaknesses. Alternatively, the essential knowledge is not the TENDL library itself, but rather the necessary method and tools, making the library a side product and focusing the efforts on the evaluation knowledge. The future of such approach will be discussed with the hope of nearby greater success.

A study of direct neutron induced reactions off spherical nuclei is given in terms of a folding model. Matter densities stemming from the Random Phase Approximation (RPA), implemented with the Gogny D1S force are used to provide the relevant coupling potentials. The impact of rearrangement corrections on cross sections is studied for direct inelastic nucleon scattering off 16O and 208Pb. The rearrangement correction to calculated cross sections is shown to strongly depend on the incident energy and on the excitation multipolarity.

The aim of the present study was to assess the antiatherogenic properties of Pinus pinaster (maritime pine) seed oil. To this end, the effects of P. pinaster oil supplementation on lipoprotein levels and atherosclerotic lesions were compared to those of lard or sunflower oil in apolipoprotein E-deficient mice. Plasma total cholesterol (P < 0.0001) and VLDL + intermediary density lipoprotein (IDL)-cholesterol (P < 0.0001) levels were lower in mice fed P. pinaster and sunflower oil than in those fed the lard diet. In contrast, triglycerides (P < 0.0001) and VLDL + IDL-triglycerides (P < 0.0001) levels were higher in mice fed P. pinaster oil than sunflower oil or lard. The VLDL + IDL lipid composition of apolipoprotein E-deficient mice fed P. pinaster oil was intermediate between that of lard-fed transgenic mice and that of wild-type mice fed nonpurified diet. Using the Triton WR1339 method, the fractional catabolic rate of plasma triglycerides was found to be lower in mice fed P. pinaster oil (P < 0.0001) than sunflower oil or lard diet, suggesting a defective clearance of triglycerides in the P. pinaster group. Finally, the susceptibility of triglyceride-rich lipoproteins to in vitro lipoprotein lipase-mediated tipolysis was lower in the P. pinaster oil-fed group than in the lard-fed group. Despite the differences in VLDL + IDL level and lipid composition, the surface areas of aortic atherosclerotic lesions were not significantly different among mice fed P. pinaster, sunflower or lard diets. In conclusion, the results of the present study indicated that feeding P. pinaster oil had no better preventive effect on aortic atherosclerotic lesion extension in apolipoprotein E-deficient mice than other saturated or polyunsaturated fats. KEY WORDS: apolipoprotein E-deficientmice; atherosclerosis; diet; lipoprotein; Pinus pinaster oil

The classical use of a generalized X2-distance to determine the evaluated cross section uncertainty requires the values of the experimental cross sections covariance matrix. The usual propagation error method to estimate the covariances is hardly usable and the lack of data prevents from using the direct empirical estimator. Thus we present an alternative which exploits a regression model of the experimental cross section to generate pseudo-measurements and thereby allows an estimation of experimental covariances. The problem of assessing the quality of the estimate still remains. In our approach, we propose to determine the estimation quality through the means of the bootstrap method. We show on numerical examples that the bootstrap allows to have an order of magnitude of the estimation quality through a matrix norm. All the results are illustrated with a toy model (where all quantities are known) and also with real cross-section data measurements.

In the classical use of a generalized χ2 to determine the evaluated cross section uncertainty, we need the covariance matrix of the experimental cross sections. The usual propagation error method to estimate the covariances is hardly usable and the lack of data prevents from using the direct empirical estimator. We propose in this paper to apply the kriging method which allows to estimate the covariances via the distances between the points and with some assumptions on the covariance matrix structure. All the results are illustrated with the 2555Mn nucleus measurements.

Microscopic optical model potentials for nucleon-nucleus collisions, based on density-dependent effective interactions, involve multi-dimensional integrals to account for the Fermi motion of the bound nucleons of the target. If a spherical matter distribution is assumed, each matrix element of the optical potential in momentum space requires the evaluation of seven-dimensional integrals. Here we describe the structure of these potentials and report results from their actual evaluation. Results for the scattering observables are compared with those based on alternative approximations, observing moderate sensitivity. These findings validate the use of simpler expressions to evaluate folding optical potentials, from which higher-order or unconventional effects in the effective interaction can safely be investigated.

The measurement of neutron-induced cross sections of short-lived nuclei is extremely difficult due to the radioactivity of the samples. The surrogate reaction method is an indirect way of determining cross sections for nuclear reactions that proceed through a compound nucleus. This method presents the advantage that the target material can be stable or less radioactive than the material required for a neutron-induced measurement. We have successfully used the surrogate reaction method to extract neutron-induced fission cross sections of various short-lived actinides. In this work, we investigate whether this technique can be used to determine neutron-induced capture cross sections in the rare-earth region.

The measurement of neutron-induced cross sections of short-lived nuclei is extremely difficult due to the radioactivity of the samples. The surrogate reaction method is an indirect way of determining cross sections for nuclear reactions that proceed through a compound nucleus. This method presents the advantage that the target material can be stable or less radioactive than the material required for a neutron-induced measurement. We have successfully used the surrogate reaction method to extract neutron-induced fission cross sections of various short-lived actinides. In this work, we investigate whether this technique can be used to determine neutron-induced capture cross sections in the rare-earth region.

The surrogate reaction method is an indirect way of determining cross sections for nuclear reactions that proceed through a compound nucleus. In this method, the compound nucleus is produced via an alternative (surrogate) reaction and its decay (by fission, gamma or neutron emission) is measured in coincidence with the outgoing appropriate charged particle. This technique has enabled neutron-induced cross sections to be extracted for nuclear reactions on short-lived nuclei that otherwise could not be measured. The CENBG collaboration has successfully applied this technique to determine the neutron-induced fission cross sections of several short-lived nuclei such as 233Pa, 242,243Cm and 241Am. These data are very important for the development of the Th/U cycle and for minor actinide transmutation. We currently investigate whether this powerful technique can also be used to determine the neutron-induced capture cross sections. For this purpose we will use the surrogate reaction 174Yb(3He,pγ)176Lu to infer the well known 175Lu(n,γ) cross section and compare the results with the directly measured neutron-induced data. The experimental set-up and the first results will be presented. We will also discuss our future plans to use the surrogate method for extracting actinides (n,γ) cross sections.

Determination of neutron-capture cross sections of short-lived nuclei is opening the way to understand and clarify the properties of many nuclei of interest for nuclear structure physics, nuclear astrophysics and particularly for transmutation of nuclear wastes. The surrogate approach is well-recognized as a potentially very useful method to extract neutron cross sections for low-energy compound-nuclear reactions and to overcome the difficulties related to the target radioactivity. In this work we will assess where we stand on these neutron-capture cross section measurements and how we can achieve the short-lived Minor Actinides nuclei involved in the nuclear fuel cycle. The CENBG collaboration applied the surrogate method to determine the neutron-capture cross section of 233Pa (T1/2 = 27 d). The 233Pa (n,γ) cross section is then deduced from the measured gamma decay probability of 234Pa compound nucleus formed via the surrogate 232Th(3He,p) reaction channel. The obtained cross section data, covering the neutron energy range 0.1 to 1 MeV, have been compared with the predictions of the Hauser-Feshbach statistical model. The importance of establishing benchmarks is stressed for the minor actinides region. However, the lack of desired targets led us to propose recently the 174Yb (3He,pγ) reaction as a surrogate reaction for the (n,γ) predetermined benchmark cross section of 175Lu. An overview of the experimental setup combining gamma ray detectors such as Ge and C6D6 in coincidence with light charged particles ΔE-E Telescopes will be presented and preliminary results will be discussed.

We have developed microscopic models for nucleon induced inelastic scattering and one-step direct preequilibrium emission. These models are based on reliable effective in-medium two-body interactions and a microscopic description of the ground and excited states of target nuclei. No arbitrary renormalization process enters our analyzes and the predictions are directly compared to experimental data. The nuclear structure information are obtained in the Random Phase Approximation (RPA) framework with the Gogny force, which provides accurate descriptions of spherical nuclei without pairing. For medium energy (50-200 MeV) proton induced reactions, this approach gives very good predictions for direct inelastic scattering and for the first-step in direct preequilibrium emission. The one-step preequilibrium model has also been extended to fast neutron scattering (10-20 MeV) for the 90Zr target described with RPA theory, and for axially deformed nuclei with a simpler description of the excited states (i.e. particle-hole excitations). Predictions of the reaction model reproduce well experimental data for 90Zr. For deformed targets (232Th and 238U), our calculations underestimate the data at high emission energy. The cross section missing for both actinides may stem from the excitation of vibrational states with excitation energies lower than 5 MeV which are not described with incoherent particle-hole excitations. This defect might be cured if the target spectra are described within the Quasi-particle-RPA (QRPA) theory recently implemented with the Gogny force.

We present a review of the fission cross section measurements made by the CENBG collaboration over the last years using the surrogate reaction method. For example the neutron-induced fission cross sections of 233Pa(T1/2 = 27 d), 242Cm(T1/2 d) and 243Cm(T1/2 y) have been obtained by our group with this technique. The advantages and the difficulties of the surrogate method are discussed. Special attention is paid to the comparison between cross sections measured with the surrogate method and those obtained directly with neutrons at low energies. This comparison provides information on possible differences between the spin-parity distributions achieved in the two methods.

In studies of nucleon elastic scattering, a correction to the microscopic optical potential built from Melbourne g-matrix was found to be necessary at low nucleon incident energy [1,2]. Indeed, at energies lower than 60 MeV, the absorption generated from Melbourne g-matrix is too weak within 25%. Coupling to collective excited states of the target nucleus are not included in the g-matrix and could explain the missing absorption. We propose to calculate this correction to the optical potential using the Gogny D1S effective nucleon-nucleon interaction in the coupling to excited states of the target. We use the Random Phase Approximation (RPA) description of the excited states of the target with the same interaction.

The neutrons for science (NFS) facility is a component of SPIRAL-2, the new superconducting linear accelerator built at GANIL in Caen (France). The proton and deuteron beams delivered by the accelerator will allow producing intense neutron fields in the 100 keV–40 MeV energy range. Continuous and quasi-mono-kinetic energy spectra, respectively, will be available at NFS, produced by the interaction of a deuteron beam on a thick Be converter and by the 7Li(p,n) reaction on thin converter. The pulsed neutron beam, with a flux up to two orders of magnitude higher than those of other existing time-of-flight facilities, will open new opportunities of experiments in fundamental research as well as in nuclear data measurements. In addition to the neutron beam, irradiation stations for neutron-, proton- and deuteron-induced reactions will be available for cross-sections measurements and for the irradiation of electronic devices or biological cells. NFS, whose first experiment is foreseen in 2018, will be a very powerful tool for physics, fundamental research as well as applications like the transmutation of nuclear waste, design of future fission and fusion reactors, nuclear medicine or test and development of new detectors. [ABSTRACT FROM AUTHOR]